Thank you Whirly, well said.
I confess, I rather wish this particular genie would have stayed in the bag for a little while longer (purely because I'd like some answers before telling the world what the question was), but since it's out...
MikeJ and I are both involved with a UK organisation with an objective of promoting and improving safety in GA. One of the things that has been going on lately is a review of roughly 25 years of GA fatal accidents (1980-2004); there have been well over 100 fatal accidents in the UK in that period (looking at Group A at the moment) so there's a reasonable statistical sample. (And, being brutal, an unpleasantly high body count - some of those people were friends of mine, and probably friends of other people reading this).
A very large proportion (something around 2/3) of these fatals involved, in some way, a stall and/or spin. This is not exactly surprising, but it does allow us to start analysing things statistically since we're still on big numbers.
You can see reasonable trends by type. For example the tapered wing PA28s (e.g. the PA28-161 Warrior II) show NO stall/spin related fatals in that period. On the other hand whilst the C152 shows 1 such fatal in that period, the C150 shows 10. Since in the UK the CAA helpfully retains a record of the hours flown by everything, we can standardise that by flying hours. This shows that whilst remaining generally very safe, the C150 is about 16 times more likely to suffer such an accident than the C152. The bulk of these fatal accidents appear to occur during the climb-out or go-around.
So, we're asking ourselves why? There are a few theories: many concentrating upon the flap mechanisms; but, they also include CG differences, slight wing shape differences, different profiles of the pilots flying each type - and no-doubt a few other theories will come out of the woodwork. There are other, far worse types statistically than the C150 (and far better than the C152), but the fact that they're so similar makes it relatively easy to study the differences.
There are two big reasons why we want to know the answer to this question, it's not just academic interest. These are:
(1) When we know what the reason(s) is/are, we can tell pilots on this, and other types, what mistakes to avoid.
(2) It'll also allow us to feed information to aircraft designers and evaluators so that whatever that subtle difference is between the two, we can use that knowledge to make future aeroplanes safer.
G